. >> reporter: you won't find blastic bags at the checkout counter at bob's market in southern california. they are banned in 50 cities and counties across the state. francine shops with her own reusable bag and wants more communities to enforce similar bans. >> if they went through a garbage dump or a trash site and saw what was going on they would think twice about it. >> reporter: supporters of the ban say plastic bags crowd land fills, pollute streets and waterways and threaten marine life. where plastic is banned like here in santa monica, stores go through piles of paper bags. those also take a toll on the environment but about 50% do get recycled. that's compared to about 5% of plastic bags. but manufacturers say banning the bags is unfair. >> the amount of litter nationally that plastic bags produce is less than half of 1%. >> reporter: marine scientis is with the advocacy group heal the bay and says in los angeles plastic bags make up closer to 25%. >> litter on the streets gets washed through the storm sewer system, through our waterway systems. and plastic bags are part of that